A damper is used to damp vibrations of, for example, a vehicle, a device, and a construction. For example, a damper disclosed in U.S. Pat. No. 3,837,445B includes a cylinder, an annular rod guide, an annular seat, a rod, an annular oil seal, and an annular seal holder. The cylinder internally forms an action chamber. The rod guide is secured to an upper opening of this cylinder. The seat is disposed on the action chamber side of this rod guide. The rod is inserted through insides of the rod guide and the seat so as to be axially movable. The oil seal is held to an inner periphery of the rod guide to seal an outer periphery of the rod. The seal holder is interposed between the rod guide and the seat and disposed on an outer periphery of the oil seal.
The seal holder is made of an elastic body such as rubber. The seal holder elastically supports an outer periphery of a lip portion of the oil seal to enhance a sealing property (performance of sealing) with the oil seal. The seal holder closely contacts an inner peripheral surface of the cylinder to seal an inner periphery of the cylinder. The seat includes a communication passage that axially penetrates this seat. Through a transmission of a pressure in the action chamber via this communication passage to the oil seal via the seal holder also allows enhancing the sealing property with this oil seal.
In details, when the seal holder receives the pressure in the action chamber via the communication passage, the seal holder is pressed to the rod guide and is compressed. This strengthens a force of fastening the lip portion of the oil seal with the seal holder. This ensures strongly pressing the lip portion to the outer peripheral surface of the rod, enhancing the sealing property with the oil seal.